In the art, pressure accumulators for fluids are used in a large and wide range of applications, e.g. in drinking water and process water delivery, in pressurized lubrication and, in particular, in injection systems for fuel in connection with internal combustion engines, particularly in the motor vehicle sector.
In the area of common rail engine injection, pressure accumulators for fuel which are operated at pressures of between a few hundred and a few thousand bar are used, for example. Depending on requirements, correspondingly high pressures are provided and set in the pressure accumulator.
For supplying fluid, especially liquids, to such pressure accumulators, high-pressure pumps which can themselves be controlled may be considered, on the one hand, but, on the other hand, control of the setpoint pressure by controlling the quantity of fluid fed to the pump may be considered.
Normally, at least one pressure sensor is provided in the pressure accumulator, said sensor allowing detection of the actual pressure and transmission of this information to a pressure regulating system.
Moreover, in many cases not only the removal device for using the fluid but also a pressure reduction valve, which can discharge fluid at least in the event of failure of the pressure regulating system, is provided. However, a pressure reduction valve of this kind can also be controlled in such a way that, when the pressure level in the pressure accumulator is too high, the regulating system can resort to the pressure reduction valve and can achieve a pressure reduction by that means. For this purpose, pressure reduction valves of this kind are in many cases controllable.
In the event of a failure of the high pressure sensor in the pressure accumulator too, the high requirements of the reliability of a motor vehicle or of some other system incorporating a pressure accumulator mean that continued operation must be possible. For this purpose, a “feed forward” system is provided in the motor vehicle sector, said system delivering a certain fuel quantity to the pressure accumulator via the feed device independently of any feedback from a pressure sensor.
However, faults can occur not only in the pressure sensor but also in other components of the system which has the pressure accumulator, e.g. pumps, valves, seals and the housing wall of the pressure accumulator. It is therefore desirable to create ways of checking the pressure regulation in the case of a pressure accumulator of the type described.